Technical Field
The field of this invention is compounds and their use in the treatment of prostate cancer and hyper-androgenic syndromes including alopecia, hirsutism and acne vulgaris.
Background
The existence of a number of pathologic syndromes depends on androgen hormones. Thus, growth of prostate cancer in early stages is androgen driven and can, at least temporarily, be stopped by androgen deprivation. Androgenic alopecia is caused by an unexplained switch from the growth promoting effect of androgens on the hair follicles to hair loss. In skin androgen mediated disorders, such as alopecia, acne vulgaris, and hirsutism, excess of the cutaneous androgens were shown to be the major nosological factor.
The pathophysiology of both male and female hair loss is not yet fully understood and the therapy is unsatisfactory. Factors ranging from low scalp blood flow, deficiency of nutrients and hair-related vitamins, microbially-driven inflammatory changes, etc., have been considered. It is nevertheless, apparent that the most influential factor is the effect of the androgenic hormones (AH) on the scalp hair follicles. AH are important in the physiology of skin; they promote the growth of the beard and of the body hair throughout life. The growth of the scalp hair also depends on AH but only in early life. It is not yet explained why AH, with increasing age, switch from promoting growth of the scalp hair to its loss, inducing conditions known as an androgenic effluvium (AE) and alopecia (AGA). In hirsutism and acne vulgaris, excess of cutaneous AH was shown to be the major factor in those complex syndromes.
The androgenic hormones can act only via an androgenic receptor (AR), which is a transcription factor, a protein which interacts with a specific region of DNA. Thus, the mode of action of testosterone and its much more potent analog, 5-alpha dihydrotestoterone (DHT) depends upon binding to the AR. Only then can transcription by RNA polymerase II take place. AH are derived either from the systemic circulation and/or synthesized in synthesized in the skin bind to the AR located in the hair follicles.
In the treatment of androgenic alopecia, various antiandrogens originally developed for the treatment of prostate cancer were claimed for systemic use, but side effects of chronic therapy with these systemically absorbable substances were of concern. In cutaneous afflictions anti-androgenic compositions have been tried, but with limited success, possibly because all non-steroidal compounds are resorbed by the skin and elicit systemic effects, which prevents their use in males. In the scalp, the precursors to androgens are normally converted into potent androgens, which bind to the AR in the hair follicles and promote hair growth. In genetically pre-disposed subjects however androgens at certain age cause hair loss. Clearly, a topically active composition capable of cutaneous, but not systemic resorption, and of suppressing or eliminating the AR locally, would be useful in preventing or reversing the incipient androgenic alopecia.
The current state of prostate cancer therapy (CaP), the second most prevalent malignancy in males, is unsatisfactory. When detected early, with the tumor strictly confined to the prostate gland, CaP can be often controlled by implantation of radioactive seeds, or by prostatectomy, which often results in incontinence and impotence. Locally advanced prostate cancer can often be reasonably controlled when in the pelvis and is encompassed into a single port of an external radiation beam.
For advanced CaP, the standard treatment is androgen receptor-blockade, usually in combination with LHRH superagonists, which suppresses both adrenal and testicular testosterone. The rationale of this approach is that early prostate cancer invariably depends on androgens for growth. The activity mechanism of clinically utilized antiandrogens is thought to involve blockade of the AR by binding to it and/or by interference with binding of the AR to the DNA; some agonistic compounds can even promote DNA binding but they do modify the binding domain. Thus, cyproterone acetate was found to block about 50% of AR binding to the DNA, while flutamide, bicalutamide or nilutamide, were found to completely block such binding. All of these state of the art compositions have nevertheless only limited applicability, as the primary tumor and its metastases eventually become hormonally refractory and resistant to further anti-androgenic therapy. The reason is invariably AR mutation, which can be occasionally found as a genetic deviation, but is usually a result of the AR blockade. Even when both suprarenal and testicular androgens are eliminated by chemical castration, using LHRH super agonist and/or by surgical castration, the mutated receptor retains the capability to be activated by various steroidal metabolites and even progestins and estrogens. A variety of other factors can activate the androgen receptor gene via AR activation, such as insulin-like growth factor, epidermal growth factor, and keratinocyte growth factor and neuroendocrine transmitters, such as serotonin. Therefore, blocking the AR is not an ideal treatment and a new approach is needed. It has also been shown that as a result of the AR blockade, the AR gene is amplified with the resulting overproduction of the AR. In 6 to 24 months the AR mutates and the tumor and metastases became hormone refractory and continue to grow.
The common denominator of resistance to current anti-androgens is a modification of the AR. Even after a relapse following androgen blockade therapy, experiments indicate the AR is still present and plays a major role in the propagation of CaP cells.
In selecting therapeutic options, a correct therapeutic decision can only be made if the extent of the disease is known. When CaP is confined strictly t the gland, surgery and/or local or external radiation can be curative. However, in the case of extracapsular disease, prostatectomy or radiation are not only useless, but noxious, since a high rate of serious side effects, such as impotence, incontinence and chronic inflammation of the adjacent tissues accompanies these interventions. Members of the current diagnostic armamentarium comprise digital rectal palpation, serum prostate specific antigen determination and ultrasound, magnetic resonance or x-ray imaging. These techniques cannot reliably detect CaP spread into the soft tissues. Thus, metastases to the lymph nodes cannot be reliably detected with these methods resulting in clinical understaging of 40 to 60% of the instances.
The prior art of diagnostic localizing agents for CaP teaches specific radioactively labeled antibodies, but widespread use is limited by the complexity of the procedure. 5xcex1-dihydrotestosterone labeled with 18F has been used for PET scanning, a generally inaccessible imaging modality.
There are, therefore, substantial deficiencies in both therapeutic and diagnostic approaches to the treatment of CaP. It is therefore of interest to find compounds which not only block the AR, but also diminish the number of ARs which are available. In addition, another desirable characteristic for topical purposes would be compounds which have low or no systemic resorption. Also, the compounds should degrade or be metabolized into components of low or no toxicity and have little or no anti-androgenic activity. In addition, radioisotope labeled compounds specific for neoplastic prostate cells would be of great help. These compounds would allow the physician to visualize the pathomorphology of CaP accurately, so that unnecessary and costly surgery and/or radiation is avoided in patients where CaP has progressed beyond the reach of curative surgery or the scope of a single radiation port. Other appropriate therapies, such as androgen ablation and/or unspecific chemotherapy, can then be instituted.
Systemic antiandrogens (AA) are orally administered in vivo stable compounds known to block the AH binding to AR. Originally developed for the treatment of prostate cancer, these compounds have considerable general effects since they block AR systemically, resulting among others, in loss of libido and male sexual function. The nonsteroidal agents cannot be used in males for the AE or AGA treatment at all, neither orally nor topically, since they are well absorbed from the skin and are stable in vivo. Attempts to treat male EA and AGA with topical steroidal AA such as cyproterone acetate, chlormadimone acetate and spironolactone were not successful, apparently because of poor absorption into the skin (Zaumseil, R-P.: Schering AG/Asche Corp., Hamburg Personal Communication 1997). Some antiandrogens also have a skin irritation potential.
Systemic AA were proposed for treatment of women suffering with AE and AGA (Diamanti-Kandarakis, E. Current aspects of antiandrogen therapy in women. Current Pharm Des, Sep. 5, 1999(9): 707-23), but concerns for side effects call for clinical studies. It is generally known, at least in males, that extended AR blockade leads to AR mutation, and that the mutated receptor attains the capability to be activated by other substances such as various steroidal metabolites and even progestins and estrogens, insulin-like growth factor, epidermnal growth factor and keratinocyte growth factor and neuroendocrine transmitters such as serotonin. It has also been shown that the AR blockade amplifies the AR gene. It is therefor apparent that treatment of hair loss in women by blocking AR with systemic AA is not ideal and that in men it is not acceptable at all.
Currently available for treatment of AE and AGA are the topical Minoxidil and its derivatives, and the oral finasteride (Scow, D. T.; Nolte, R. S.; Shaughnessy, A. F. Medical treatments for balding in men. American Family Physician, Apr. 15, 1999, 59(8): 2189-94, 2196). Minoxidil, an antihypertensive drug, has incidentally shown to prevent hair loss, and to an extent promote regrowth, but only in the vertex scalp, the activity is tentatively explained by activation of the prostaglandin endoperoxide synthase-1, increase for the local blood flow, suppression of bacterial infection and/or by a modification of the AH metabolism in the dermal papilla. (Michelet, J. F.; Commo, S.; Billoni, N.; Mah, Y. F.; Bernard, B. A. Activation of cytoprotective prostaglandin synthase-1 by minoxidil as a possible explanation for its hair growth-stimulating effect. Journal of Investigative Dermatology, February 1997, 109(2): 205-9; Pirard-Franchimont, C.; DeDoncker, P.; Cauwenbeergh, G.; Pirard, G. E.: Ketoconazole shampoo: effect of long-term use in androgenic alopecia. Dermatology, 1998; 196 (4): 474-7; Sato, T.; Tadokoro, T.; Soroda, T.; Asada, Y.; Itami, S.; Takayasu, S. Minoxidil increases 17 beta-hydroxysteroid dehydrogenase and 5 alpha-reductase activity of cultured human dermal papilla cells from balding scalp. Journal of Dermatological Science, Feb. 19, 1999(2): 123-5).
Finasteride taken orally and daily suppresses conversion of testosterone into dihydrotestosterone (DHT), thus lowering AH activity in the scalp. The studies indicate about half of the men achieve slight to moderate improvement in the anterior mid scalp and in approximately one-half, the effluvium is arrested. Side effects include decreased libido and erectile function, which disappear after drug withdrawal. (Kaufman, K. D.; Olsen, E. A.; Whiting, D.; Roberts, J. L.; Hordinsky, M.; Shapiro, J.; Binkowitz, B.; Gormley, G. J. Finasteride in the Treatment of Men with Androgenic Alopecia. Finasteride Male Pattern Hair Loss Study Group. Journal of the American Academy of Dermatology. October 1998, 39 (4 Pt. 1): 578-89). No studies are yet available to prove whether such a long term systemic manipulation is hormonal balance is harmless.
Clearly a topically active antiandrogen suppressing rather than blocking the cutaneous AR, while not irritating and not systemically absorbable would be useful in the therapy of AH dependent cutaneous afflictions.
We designed and synthesized a number of novel compounds with potential antiandrogen activity and unexpectedly found that some, rather than blocking suppressed the AR, by a concentration and time dependent fashion. (Sovak, M. S.; Bressi, J. C.; Douglas, J.; Campion, B.; Wrasidlo, W. Androgenic Directed Compositions, U.S. application Ser. No. 09/215,351, 1998) Some of these compounds showed extremely low or no systemic bioavailability upon topical application. Furthermore, BP-766 proved to be biodegradable into components devoid of antiandrogenic activity and having low systemic toxicity. The topically active and not systemically absorbable suppressor of cutaneous androgen receptors is described herein. It offers a sound therapeutic concept in androgenic effluvium and alopecia, both in males and females.
Relevant Literature
U.S. Pat. No. 5,656,651 and WO97/00071, and references cited therein, describe anti-androgenic directed compositions based on phenyldimethylhydantoins, where the phenyl group is substituted with a trifluoromethyl group and either a cyano or nitro group. See also, Battmann et al., J. Steroid Biochem. Molec. Biol. 64:103-111 (1998); Cousty-Berlin, ibid 51:47-55 (1994); and Battmann et al., ibid 48:55-60 (1994), for a description of analogous compounds and their activity. For other compounds having the substituted phenyl moiety, see U.S. Pat. Nos. 4,636,505 and 4,880,839, and EP 0 100 172. For discussions about the activities of antiandrogens, see Kuil and Brinkmann, Eur. Urol. 29:78-82 (1996); Kondo et al., Prostate 29:146-152 (1996), and Simard, et al., Urology 49:580-589 (1997). For discussions about alopecia and its relationship with androgens, see Kaufman, Dermatologic Clinics 14:697-711 (1996); Toney et al., J. Steroid Biochem. Molec. Biol. 60:131-136 (1997); Brouwer et al., J. of Dermatology 137:699-702 (1997); and Shapiro and Price Dermatologic Clinics 16:341-356 (1998).